Fuel cell and internal combustion engine vehicles powered by hydrogen gas may include on board high pressure gas fuel tanks that may include gas absorbing materials within the tank interior. In previous applications for United States Letters patent, I have described that during driving, gas remaining in a tank becomes cold when tank pressure decreases as gas is consumed by the vehicle power plant and the tank decompresses. In cold climates, the tank internal gas temperature can drop to −60° C. or below, a temperature that may be below the permissible operating temperature of O-rings, or other rubber seals, or gas flow controls in the tank assembly. An excessively low temperature in the tank may upset design tolerance limits for the seals and flow controls and cause the stored gas to leak as a result of temperature caused stresses in the tank system assembly. For example, when the ambient temperature is −20° C., the reduction of internal tank temperature by an additional −40° C. due to gas decompression effects will result in an internal temperature in the gas tank of −60° C. or below. Expansion and contraction of the tank and the component parts of the gas flow system associated with the tank may produce adverse mechanical stress effects.
Hydrogen gas generates heat when the pressure of gas maintained under high pressure decreases to a level approximating the lower pressure in a gas flow line. This phenomenon is known as the Joule-Thomson effect, singular to hydrogen and helium, and is used in the invention to recycle the mechanical energy of heat compression in the hydrogen fuel stored in a tank during the refill process to warm the gas and/or the tank assembly as the decompression energy stored in the gas is utilized during the driving condition of a vehicle.